The vertebrate retina is investigated as a model for neural organization in the central nervous system. A major effort is directed toward understanding cellular pathways and synaptic mechanisms involved in color vision. Goldfish are chosen because they have trichromatic color vision based on three cone visual pigments, and because the color-coded activities of their large ganglion cells and some intermediate retinal neurons are also known in part. Previously we have shown that the cone pigments are contained in structurally distinctive cones. We have used this information to analyze color-coded pathways of bipolar cells and horizontal cells, stained by the Golgi method and examined in the light or electron microscope. We propose now: to complete analyses of interreceptor contacts between cones and of interconnections between horizontal and interplexiform cells; to begin circuitry analysis of the inner synaptic layer in goldfish; and to extend these studies to another animal, the turtle, in which functions of single cells related to color vision also are known. Finally we shall undertake microscopic analyses of neurogenesis in retinas of selected teleosts and mammals, in an attempt to understand the temporal ordering of neuronal differentiation and specification of cone- and rod-specific neuronal interconnections.